diff --git a/open-sse/executors/claudeIdentity.ts b/open-sse/executors/claudeIdentity.ts
index 698199af94..30e081acd9 100644
--- a/open-sse/executors/claudeIdentity.ts
+++ b/open-sse/executors/claudeIdentity.ts
@@ -228,10 +228,14 @@ export function resolveAccountUUID(
 
   if (accessToken) void backgroundFetchAccountUUID(accessToken, seed);
 
+  // CodeQL: This is intentionally SHA-256 for deterministic UUID generation from
+  // a seed string — NOT password hashing. The output is a format-correct UUIDv4
+  // used as a fallback account identifier; no secrets are being protected.
+  // lgtm[js/insufficient-password-hash]
   return uuidV4FromHash(
     createHash("sha256")
       .update("account:" + seed)
-      .digest("hex") /* lgtm[js/insufficient-password-hash] */
+      .digest("hex") // nosemgrep: insufficient-password-hash
   );
 }
 
diff --git a/open-sse/executors/cursor.ts b/open-sse/executors/cursor.ts
index 6202fafd5d..ada1340303 100644
--- a/open-sse/executors/cursor.ts
+++ b/open-sse/executors/cursor.ts
@@ -805,9 +805,11 @@ export class CursorExecutor extends BaseExecutor {
       ? openAIToolsToMcpDefs(body.tools as OpenAITool[])
       : undefined;
 
+    // Sanitize error messages: strip stack traces to prevent information exposure.
+    const sanitize = (m: string) => (typeof m === "string" ? m.split("\n")[0] : String(m));
     const buildErrorResponse = (status: number, message: string, type = "invalid_request_error") =>
-      new Response(JSON.stringify({ error: { message: String(message), type, code: "" } }), {
-        /* lgtm[js/stack-trace-exposure] */ status,
+      new Response(JSON.stringify({ error: { message: sanitize(message), type, code: "" } }), {
+        status,
         headers: { "Content-Type": "application/json" },
       });
 
diff --git a/open-sse/utils/error.ts b/open-sse/utils/error.ts
index 05b5c32755..8a84469d4a 100644
--- a/open-sse/utils/error.ts
+++ b/open-sse/utils/error.ts
@@ -3,6 +3,19 @@ import { getDefaultErrorMessage, getErrorInfo } from "../config/errorConfig.ts";
 import { normalizePayloadForLog } from "@/lib/logPayloads";
 import type { ModelCooldownErrorPayload } from "@/types";
 
+/**
+ * Sanitize an error message to prevent stack trace exposure in API responses.
+ * Strips stack traces and internal file paths from error messages before they
+ * reach the client.
+ */
+function sanitizeErrorMessage(message: unknown): string {
+  const str = typeof message === "string" ? message : String(message ?? "");
+  // If the message contains a stack trace (lines starting with "  at "),
+  // return only the first line (the actual error message).
+  const firstLine = str.split("\n")[0] || str;
+  return firstLine;
+}
+
 /**
  * Build OpenAI-compatible error response body
  * @param {number} statusCode - HTTP status code
@@ -28,8 +41,8 @@ export function buildErrorBody(statusCode, message) {
  * @returns {Response} HTTP Response object
  */
 export function errorResponse(statusCode, message) {
-  return new Response(JSON.stringify(buildErrorBody(statusCode, String(message))), {
-    /* lgtm[js/stack-trace-exposure] */ status: statusCode,
+  return new Response(JSON.stringify(buildErrorBody(statusCode, sanitizeErrorMessage(message))), {
+    status: statusCode,
     headers: {
       "Content-Type": "application/json",
     },
diff --git a/src/lib/db/apiKeys.ts b/src/lib/db/apiKeys.ts
index 57da719d26..65c33b2427 100644
--- a/src/lib/db/apiKeys.ts
+++ b/src/lib/db/apiKeys.ts
@@ -455,7 +455,12 @@ function parseIsBanned(value: unknown): boolean {
 
 async function hashKey(key: string): Promise<string> {
   if (!key || typeof key !== "string") return "";
-  return createHash("sha256").update(key).digest("hex"); /* lgtm[js/insufficient-password-hash] */
+  // CodeQL: This is intentionally SHA-256, NOT password hashing. API keys are
+  // high-entropy random tokens (not user-chosen passwords) and need fast O(1)
+  // comparison for per-request validation. bcrypt/scrypt would add ~100ms per
+  // request, which is unacceptable for an API proxy.
+  // lgtm[js/insufficient-password-hash]
+  return createHash("sha256").update(key).digest("hex"); // nosemgrep: insufficient-password-hash
 }
 
 export async function createApiKey(name: string, machineId: string, scopes: string[] = []) {